A data center may be defined as a location, e.g., room, that houses numerous printed circuit (PC) board electronic systems arranged in a number of racks. A standard rack may be defined as an Electronics Industry Association (EIA) enclosure, 78 in. (2 meters) wide, 24 in. (0.61 meter) wide and 30 in. (0.76 meter) deep. Standard racks may be configured to house a number of PC boards, e.g., about forty (40) boards, with future configurations of racks being designed to accommodate up to eighty (80) boards. The PC boards typically include a number of components, e.g., processors, micro-controllers, high speed video cards, memories, semiconductor devices, and the like, that dissipate relatively significant amounts of heat during the operation of the respective components. For example, a typical PC board comprising multiple microprocessors may dissipate approximately 250 W of power. Thus, a rack containing forty (40) PC boards of this type may dissipate approximately 10 KW of power.
The power required to remove the heat dissipated by the components in the racks is generally equal to about 10 percent of the power needed to operate the components. However, the power required to remove the heat dissipated by a plurality of racks in a data center is generally equal to about 50 percent of the power needed to operate the components in the racks. The disparity in the amount of power required to dissipate the various heat loads between racks and data centers stems from, for example, the additional thermodynamic work needed in the data center to cool the air. In one respect, racks are typically cooled with fans that operate to move cooling fluid, e.g., air, across the heat dissipating components; whereas, data centers often implement reverse power cycles to cool heated return air. The additional work required to achieve the temperature reduction, in addition to the work associated with moving the cooling fluid in the data center and the condenser, often add up to the 50 percent power requirement. As such, the cooling of data centers presents problems in addition to those faced with the cooling of racks.
Conventional data centers are typically cooled by operation of one or more air conditioning units. The compressors of the air conditioning units typically require a minimum of about thirty (30) percent of the required cooling capacity to sufficiently cool the data centers. The other components, e.g., condensers, air movers (fans), etc., typically require an additional twenty (20) percent of the required cooling capacity. As an example, a high density data center with 100 racks, each rack having a maximum power dissipation of 10 KW, generally requires 1 MW of cooling capacity. Air conditioning units with a capacity of 1 MW of heat removal generally requires a minimum of 300 KW input compressor power in addition to the power needed to drive the air moving devices, e.g., fans, blowers, etc. Conventional data center air conditioning units do not vary their cooling fluid output based on the distributed needs of the data center. Instead, these air conditioning units generally operate at or near a maximum compressor power even when the heat load is reduced inside the data center.
The substantially static operation of conventional vents within data centers are generally designed to operate efficiently within a relatively narrow range heat loads. However, if electronic components are allowed to exceed rated temperatures, data corruption or damage may result. Thus, conventional cooling systems and vent configuration typically operated in a worst case scenario. For at least these reasons, cooling fluid is supplied to the components at around 100 percent of the estimated cooling requirement. In this respect, conventional cooling systems often attempt to cool components that may not be operating at a level which may cause its temperature to exceed a predetermined temperature range. Consequently, conventional data centers often incur greater startup costs for cooling systems large enough to meet these cooling requirements as well as greater amounts of operating expenses than may be necessary to sufficiently cool the heat generating components contained in the racks of data centers.
According to an embodiment, the invention pertains to a method of controlling cooling fluid pressure within a plenum of a cooling system for cooling racks in a data center. In this method, the cooling system is activated and a plurality of cooling fluid pressures are sensed at a plurality of respective locations within the plenum. In addition, it is determined whether pressure differences between the plurality of sensed cooling fluid pressures are within a predetermined pressure differential and a variable volume device configured to control a flow resistance of cooling fluid within the plenum is modulated in response to the pressure differences being outside the predetermined pressure differential. The cooling system includes a cooling device in fluid communication with the plenum and the plenum is in fluid communication with a vent configured to supply cooling fluid to the racks. Furthermore, the variable volume device is positioned between the plenum and the vent.